It will be described in its place, but just to show that this plant can move of its own accord, it is only necessary to hold a lighted or burning match about an inch or so below the end of a long leaf. If one does this then all the little leaflets begin to fold up, and finally the main stalk droops; soon afterwards other leaves higher up the stalk begin to be affected in the same way, and fall limply down one after the other. It is supposed that this movement frightens a grazing animal, who will imagine there is something uncanny about the plant and leave it alone. There are many respects in which this reaction of the Sensitive Plant resembles that found in animals. It does not take place if the plant is chloroformed or treated with ether; the leaves also get "fatigued" if too often handled, and refuse to rise up again. There are, however, only a very few plants in which an immediate, visible answer to a stimulus can be detected. But all plants are at work; they have periods of rest which correspond to our sleep, but during their ordinary working hours they never slacken off, but continue vigorously active. The life of man is so short that it is difficult to realize all that is being done by the world of plants. It is necessary to get beyond our human ideas of time. That is most conveniently done by considering how our plant world would strike an inhabitant of the planet Neptune. Our theoretical Neptunian would be accustomed to a year of 60,127 days (164 of our years); we will suppose that three of our years are a Neptunian week, and that ten of our days are about three-quarters of a Neptunian hour, whilst two earth-hours would be a minute to him. If such a being were to observe our earth, he would be astonished at the rapidity of our vegetable world. The buds would seem to him to swell visibly; in the course of an hour or two, the bare boughs of the trees would clothe themselves with the luxuriant greenery of midsummer. Hops would fly round and round their poles, climbing at the rate of a foot a minute. Bare places, such as the gravel heaps near a sandpit, or the bare railroad tracks at a siding, would be perhaps in one week entirely covered by rich grass and wild flowers. In six Neptunian months a forest of graceful larches would spring up to a height of seventy or eighty feet. So that, if one thinks Neptunially, the activity of plants can be easily realized. The truth is that we are so familiar with common annual events, such as the regular harvest every year, that we never seem to realize what it means. There are some 1,400,000,000 human beings on the earth to-day, and they entirely depend on the work done every year by cultivated and wild plants.